Extendable boom



Aug., 27, W68 H. K. NANSEL EXTENDABLE BOOM Filed Dec. 21, 1966 2 Sheets-Sheet l Aug. 27, 1968 H. K. NANSEL 3,398,492

EXTENDABLE BOOM Filed Dec. 21, 1966 2 SheetsSheet p United States Patent 3,398,492 EXTENDABLE BOOM Harold K. Nansel, Waverly, Nebr., assignor to National Crane Corporation, Waverly, Nebn, a corporation of Nebraska Filed Dec. 21, 1966, Ser. No. 603,521 9 Claims. (Cl. 52-115) ABSTRACT OF THE DISCLOSURE An apparatus having telescoping sections powered by a telescoping hydraulic cylinder system. Mechanical latches are used to limit extension and retraction of the sections.

The relevant prior art to this invention includes applicants Patent No. 3,250,182, May 10, 1966, entitled Multiple Extension Apparatus. The unit in this patent required the use of check valves to control the extension and retraction of the multiple sections. The power required to operate the extension through the check valves was substantially greater than that required by the present invention using locking latches between the cooperating sections.

This invention may be summarized as including a plurality of telescoping sections which are extended and retracted by a power cylinder, the stronger sections being extended first and the weaker or innermost sections being retracted first. The extension and retraction of the sections causes the hold-in and hold-out latches respectively to be automatically operated and thereby providing the sequential expansion and retraction of the boom sections. One set of mechanical latches limits extension of adjacent sections, the innermost section being extended first while another set of mechanical latches limits the retraction of the boom sections, the innermost section being retracted first. The latches are automatically sequentially actuated. As one boom section moves to the limit of its extension or retraction, it causes the operation of the appropriate latch for permitting the next boom section to be operated. The sequence of operation is con tinued until the boom is fully extended or fully retraoted.

These and other features and advantages of this invention will become readily apparent to those skilled in the art upon reference to the following description when taken into consideration with the accompanying drawings, wherein:

FIG. 1 is a fragmentary cross-sectional view of the boom sections in their extended positions;

FIG. 2 is a cross-sectional view taken along line 2-2 in FIG. 1;

FIG. 3 is a fragmentary cross-sectional view showing the boom sections in their extended positions and in the dash line positions the positions of each individual section just prior to beginning this extension movement are illustrated;

FIG. 4 is a longitudinal side elevation view of the boom section in their extended positions;

FIG. 5 is a fragmentary cross-sectional view taken along line 5-5 in FIG. 1;

FIG. 6 is an enlarged fragmentary view of the hold-in and hold-out latch members and the actuating member carried by an adjacent boom section;

"ice

FIG. 7 is a fragmentary perspective view of the holdin and hold-out latch members engaged by an actuating member when the boom sections are in their fully retracted positions.

The extendable boom of this invention is generally referred to in FIG. 4 by the reference numeral 10 and includes a first or base section 12 and an outer end section 14 with intermediate sections 16, 18 and 20.

The boom sections are telescopically interconnected and as seen in FIG. 2 a telescoping hydraulic cylinder 22 extends along the longitudinal axial center of.the boom and is anchored by fastener 24 to the base of the first section 12 at the power cylinders lower end and is secured by a pin 26 to the outer end section 14. The power cylinder system includes a base cylinder 28 with successively smaller telescoping cylinder sections 30, 32 and 34 which are sequentially connected to the outer piston rod 36 anchored by the pin 26 to the boom section 14.

The extendable boom 10 includes at its lower end a pair of spaced apart mounting ears 40 and at its outer end an arm 42 is connected to the outer end section 14 and has a pulley 44 provided thereon.

As seen in FIGS. 1 and 3 the boom sections 16, 18, 20 and 14 have latch assemblies 46, 48, 50 and 52 respec tively. The latch assemblies in the intermediate booms 16 and 18 are identical except that the latch assembly 50 in section 16 is proportionately smaller.

In the various latch assemblies there are hold-out latch members 54, 56 and 58 which extend downwardly as viewed in FIG. 3 and which are positioned in boom sections 16 and 18 opposite hold-in latch members 60 and 62. The outer boom section 14 also has a single latch member which is a hold-out latch member 64.

The hold-out bar 54 in boom section 16 is biased outwardly by a pair of springs 66 and the outer end of the latch member extends through an opening 68 in the side wall of the boom section 16. An outer shoulder portion 70 is adapted to extend through an opening 72 in the side wall of boom section 12 and lockingly engage the bottom edge 74 to hold the boom sections 12 and 16 in an extended position. A notch 76 with outwardly flaring side walls 78 is formed on the side facing the boom section 18 to matingly receive an actuating plate member 80 on the inner end of the boom section 1 8. The actuating plate member 80 includes outwardly tapering side edges 82 for mating engagement with the flared side edges 78 of the hold-out latch member 54. The tapered edge 82 is aligned at its innermost point 84 to engage the corresponding flared side edge 78 and as the boom section 18 moves further inwardly toward its retracted position the latch member 54 is moved to its retracted position of FIG. 1 whereby the actuating member 80 is fully seated in the notch 76.

Moving outwardly along the boom it is seen that the latch assembly 48 includes both a hold-out latch member 56 and a hold-in latch member 60. A portion 86 of the latch member 56 rides over the outer edge of the hold-in latch plate member 60. The latch member 60 is interconnected with the latch member 56 by a pair of springs 88 which are the expansion type and tend to spread the latch members apart. The latch member 56 is otherwise the same in design as the latch member 54 such that it has a notch 76 and a locking shoulder 70 which extends through an opening 90 in the side wall of the boom section 16. The hold-in latch member 60 extends through an opening in the side wall of the boom section 18 and has a tapered outer side edge 92 for slidable mating engagement with a tapered shoulder 94 of an actuating shoulder 96 on the inner side of boom section 12. As the boom section 16 moves outwardly the shoulder 92 engages the actuating shoulder 96 and moves the hold-in bar 60 inwardly thereby permitting the boom section 18 to extend relative to the boom section 16 as the hold-in bar 60 is moved out of a lock opening 98 for-med in the side wall of the boom section 16.

The hold-in latch member 62 and the hold-out latch member 58 in the latch assembly 50 carried by the boom section 20 operates in the same manner as latch assembly 48 in the boom section 18; however, the hold-in latch member 62 is movable through an opening 100 formed in boomsection 18 for engagement with an actuating shoulder 102 and the hold-out latch member 58 is movable through an opening 104 in the boom section 18. An actuating tongue plate member 106 is provided on the inner end of the boom section 20 for actuating the latch plate assembly 48 and specifically seating in the notch 76 in the hold-out latch plate 56. The outermost boom section 14 has a hold-in latch member 52 only which is similar to the other hold-in latch members 60 and 62 but is movable through an opening 107 in the side wall of boom section 20 for engagement with an actuating shoulder 108 on the inner side of the side wall of boom section 18. An actuating tongue plate member 110 is provided on the inner end of the boom section 14 for matingly being seated in the notch 112 formed in the hold-out latch plate member 58 carried in boom section 20.

To prevent the hold-out 'latch plate members 54, 56 and 58 from falling out of the boom sections, keeper members 120 are provided which extend over the openings 72, 90 and 104.

On opposite sides of the boom sections guide blocks 122 are provided adjacent the outer ends of the respective sections. The guide blocks 122 on the bottom side of the boom as viewed in FIG. are adapted to be engaged by stop shoulders 124 on the outer side walls of boom sections 14, 16, 18 and 20 to limit the extension of the respective sections. It is noted that the hydraulic cylinder 22 through its respective telescoping sections 30, 32 and 34 also will serve to limit the outward extension of the boom sections.

In operation, it is seen from FIG. 6 that the boom section 20 is held against being telescoped to a retracted position within boom section .18 by the hold-out latch member 58 extending through the opening 104 in the side wall of boom section 18. In this position the hold-in latch member 62 is inoperative and the actuating tongue plate member 110 on the outer boom section 14 is about to actuate the hold-out member 58 to retract it from the lock opening 104 and thereby permit the retraction of the boom section within the boom section 18. In FIG. 7 the latch assembly 50 in boom section 20 and the latch assembly 52 in boom section 14 are illustrated as they appear when the boom section 14 is retracted into the boom section 20. The actuating tongue member 110 has seated in the notch 112 in the hold-out latch member 58 and consequently has moved it out of the opening 104 and thus the boom section 20 is now ready to be retracted within the boom section 18.

When the boom sections are being extended it is appreciated that the actuating shoulders 96, 102 and 108 are located relative to the hold-in latch members 60, 62 and 64 such that they are actuated just before the boom section being extended reaches its forward extended position and thereby the next boom section is permitted to be extended.

Some changes may be made in the construction and arrangement of my extendable boom without departing from 4- the real spirit and purposeof my invention, and it ismy intention to cover by my claims, any modified forms of structure or use of mechanical equivalents which may be reasonably included within their scope.

I claim: a

1. An extendable boom, comprising:

a plurality of sections telescopically interconnected and including a base first section; a se cond'section movable therein, and a thirdsection movable within said second section,

power means for extending and retracting said sections,

a laterally movable hold-out means in said second section and a cooperating lock means on said-first section engageable therewith upon said second section being extended relative to said first section, and

an actuating means on said third section adapted to engage said hold-out means when said third section is retracted relative to said second section, said actu ating means moving saidhold-out means laterally out of engagement .with said lock means to permit retraction of said second section relative to said first section.

2. The structure of claim 1 wherein said third section includes a laterally movable hold-in member engageable with an actuating means on said first section positioned for engagement as said second section approaches its extended position.

3. The structure of claim 2 wherein said hold-in member is in locking engagement with a stop means on said second section until disengaged therefrom by said actuating means on said first section thereby holding said third section in a retracted position until said second section has been substantially extended.

4. The structure of claim 3 wherein said third section includes a laterally movable hold-out member engageable with a stop means on said second section when said third section is extended, and release means for retracting said third section hold-out member.

5. The structure of claim 1 wherein said actuating means on said third section is further defined as a tongue-shaped member extending from the inner end of said third section, and said hold-out means in said second section is a member provided with a recess opening towards said tongue and having an outwardly flaring sidewall for engagement with said tongue, a spring means biasing said hold-out member laterallyoutwardly, said tongue member being aligned to engage said flared side wall when said hold-out member is in its extended position and retract said hold-out member as-said tongue seats in said recess.

6. The structure of claim 5 wherein said third section includes laterally movable hold-in and hold-out members, said hold-in member being engageable with an actuating means on said first section positioned for engagement as said second section approaches its extended position, said hold-in and hold-out members are oppositely disposed and interconnected by an expansion spring tending to bias each of said members laterally outwardly.

7. The structure of claim 6 wherein a pair of guide openings are formed in opposite sides of said third section, and said hold-in and hold-out members are movable therethrough, said hold-out member has a transverse portion extending lengthwise of and in slidable engagement with said hold-in member, said hold-out member having a recess facing in the direction of the outer end of said third section, said recess having an outwardly flaring side edge, and a fourth section longitudinally movable within said third section and having a longitudinally inwardly extending actuating member positioned to engage the outwardly flaring side edge and retract said hold-out member as said tongue seats in said recess.

8. The structure of claim 7 wherein said first, second and third sections have stop shoulders on one of their inner sides adjacent their outer-ends, said second, third and fourth sections have stop shoulders on their outer surfaces adjacent their inner ends for engagement with 5 6 said first mentioned shoulders when said first, second and References Cited third sections are extended. UNITED STATES PATENTS 9. The structure of claim 7 wherein said sections are rectangular in cross-section and said power means is 21 1,526,563 2/1925 Powers et a1 92 19 hydraulic cylinder system extending along substantially 5 39007317 10/1961 Suderow 52-115 X the longitudinal axial center of said telescoping sections, 3,250,182 5/1966 Nansel 92-20 X said cylinder system being anchored at one end to said first section and means connecting said cylinder system at MARTIN SCHWADRON Pnmary Exammer' its opposite end with said fourth section. CARROLL B. DORITY, Assistant Examiner. 

